In today's daylight hours, we celebrate the Proerosia. From my post about the Eleusinian festivals:

"The Proerosia (Προηροσία) was a festival for Demeter’s blessings in preparation for the ploughing and sowing at the beginning of the agricultural season. In ancient times it was held at Eleusis. The name serves to convey the essence of the rites: 'sacrifice before ploughing'.

The myth goes that the whole of Hellas was suffering from a terrible famine or plague, and the oracle of Delphi was visited to ask how to stop this terrible affair, and the Delphic Oracle said that Apollon ordered a tithe to Demeter of the first harvest on behalf of all Hellenes. Except for disruptions during the Peloponnesian War, offerings arrived annually at Eleusis from all over Hellas. While Athens wasn't a big contributor to the rites--perhaps because they already made their own offerings of grain and first fruits to Demeter--most other city-states contributed generously, and the Athenians were welcome during the rites. For His help, Pythian Apollon also receives an offering during the Proerosia.

There is some confusion over the dating of the festival. Many modern sources date the festival on the fifth of Pyanpesion, but new research shows that, because of the placement of the Pyanepsia festival, in honor of Apollon and Theseus, the Proerosia could only have been celebrated in the daylight hours of the sixth.

The festival can be celebrated with first fruit-offerings, any offering related to grains (like bread, cakes, or pancakes), or a kykeon libation. The kykeon was made of barley, water, herbs, and ground goat cheese. Sometimes honey was added. Herbs that are described as part of the kykeon are mint, pennyroyal and thyme, although it seems any herb that was found to flavor the drink was acceptable."